The urinary beta-trace protein in the diagnosis of type 2 diabetic renal injury

Abstract

Objective To study the potential use of the urinary beta-trace protein ( βTP) for diagnosis of type 2 diabetic renal injury.Methods 174 patients with type 2 diabetic mellitus (T2DM) were classified into 2 groups according to the ratio of urinary albumin to creatinine (Alb/Cr):diabetes without renal injury group (group A) and diabetes with renal injury group (group B).70 healthy subjects served as normal control group ( group C).The level of urinary βTP and αl microglobulin (α1MG) was measured by latex particle enhanced immunoturbidimetry assay.The urinary Alb and Cr were determined by nephelometry and Jaffe method respectively.The level of uriuary βTP among all groups was compared and ROC curve analysis was performed.The relevant analysis on urinary βTP,urinary α1MG and other related indexes was made.Results The median level of urinary βTP/Cr in group B was 9.1mg/g Cr,significantly higher than 3.1mg/g Cr of group A and 2.0mg/g Cr of group C.The difference had statistical significance ( H =45.5,P ＜ 0.01).The other indexes ( Alb/Cr,α1MG/Cr,SCr) were all higher in group B than in the other 2 groups ( H =110.9,38.3,11.4 respectively,P ＜0.01).The relevant analysis showed that urinary βTP/Cr was positively correlated with urinary α1MG/Cr (r =0.894,P ＜ 0.01),SCr (r =0.367,P ＜ 0.05 ),HbA(J) C ( r =0.242,P ＜ 0.05 ),systolic pressure ( r =0.162,P ＜0.05 ),and the course of the disease ( r =0.251,P ＜ 0.05 ).No correlation was found between urinary βTP/Cr and diastolic pressure,fasting blood glucose(FBG) or BMI.ROC curve analysis showed the area under the curve (AUC) was 0.86 (95％CI,0.78-0.93)for urinary βTP/Cr and 0.76 (95％ CI,0.67-0.85) for urinary α1MG/Cr.The best cut-off value of urinary βTP/Cr and α1MG/Cr was 4.1mg/g Cr vs 10.9mg/g Cr,the sensitivity was 68.5％ vs 59.7％,and the specificity was 89.8％ vs 80.3％.The difference had statistical significance (P ＜ 0.05).Conclusions Urinary βTP has better diagnostic value for type 2 diabetic patients with renal injury than urinary α1MG.It can sensitively reflect renal tubular injury and can be used as a novel available biomarker to evaluate the renal tubular injury in clinic. Key words: Diabetic nephropathy ; Beta-trace protein; α1microglobulin; Urine